Netherlands: People with higher blood levels of vitamin B12 are at an increased risk of early death, a recent study in the journal JAMA Network Open has suggested. The death risk in such people was found to be almost twice as compared to those having lower B12 levels.
The researchers were surprised to find that the risk persisted even after adjusting for age, sex, renal function, and other comorbidities, such as a history of cancer.
Vitamin B12 is a hydrosoluble vitamin that plays a substantial role in 1-carbon metabolism useful for maintaining blood and nerve health. While the deleterious effects of vitamin B12 deficiency, such as anemia, neuropsychiatric symptoms, and other clinical manifestations, are well established, the potential association of high plasma concentrations of vitamin B12 with adverse health outcomes has not been fully explored
Jose L. Flores-Guerrero, University of Groningen, Groningen, the Netherlands, and colleagues, therefore, aimed to assess the association of plasma concentrations of vitamin B12 with all-cause mortality in this population-based cohort study. In addition, they also investigated whether findings were further associated with chronic kidney disease (CKD) or age, considering that approximately 35% of the elderly population has some degree of CKD.
This longitudinal cohort study used post hoc analysis to examine data from participants of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study -- a prospective population-based cohort study in the city of Groningen, the Netherlands. People who completed the second screening visit beginning January 1, 2001, were included and those who were missing values of vitamin B12 plasma concentrations or used vitamin B12 supplementation were excluded. Follow-up time was defined between the beginning of the second screening round to end of follow-up on January 1, 2011. Data analysis was conducted from October 2, 2018, to February 22, 2019.
A total of 5571 participants (mean [SD] age, 53.5 [12.0] years; 2830 [50.8%] men) were included in analyses. Median (interquartile range) plasma concentration of vitamin B12 was 394.42 (310.38-497.42) pg/mL.
Key findings of the study include:
During the median (interquartile range) of 8.2 (7.7-8.9) years of follow-up, 226 participants (4.1%) died.
According to quartiles of the distribution of plasma vitamin B12 concentration levels, mortality rates were 33.8 deaths per 10 000 person-years for the quartile with the lowest plasma concentration of vitamin B12 and 65.7 deaths per 10 000 person-years for the quartile with the highest plasma concentration of vitamin B12.
After adjustment for multiple clinical and laboratory variables,
Cox regression analyses found a significant association between higher vitamin B12 plasma concentration level and increased risk of all-cause mortality (hazard ratio per 1-SD increase, 1.25).
"Further investigation is needed to unravel the complexity of 1-carbon metabolism in different mortality causes, such as cardiometabolic disease and cancer," wrote the authors.
The study, "Association of Plasma Concentration of Vitamin B12 With All-Cause Mortality in the General Population in the Netherlands," is published in the journal JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2019.19274